From DE 10 2005 048 737 A1 an actuating device for a torque transmission device of this type is known, which is provided for actuating a dual friction clutch device which comprises a first friction clutch assembly associated with a first actuating element of the actuating device, and a second friction clutch assembly associated with a second actuating element of the actuating device. A particular feature of the known actuating device is that the two friction clutch assemblies cannot be actuated independently of one another, since the two actuating elements are displaced axially in opposite directions by a rotary member separate from the actuating elements and the supporting elements. Between the rotary member and the supporting element there act two compensation springs made as compression springs, which together with actuation reaction forces or restoring forces on the part of the friction clutch device, compensate the respective friction clutch assembly more exactly, partially or completely in relation to the respective actuating element depending on the rotation angle, so that in a central rotation angle zone of the rotation displacement range of the rotary member, which is referred to in the publication as the coupling and drive element, a resultant rotational force on the rotary member disappears, but increases quantitatively in the direction towards the angular limits of the rotation displacement range and acts in the direction of an approach toward the angular limit. The central feature of this special design is the at least partial reciprocal compensation, on the one hand of the actuation reaction forces or restoring force from one of the friction clutch assembles, and on the other hand of the actuation forces or restoring forces of the other friction clutch assembly.
From DE 10 2006 010 248 A6 it is known per se to impart to a clutch system of the “Normally Open” (or NO) type the character of a clutch system of the “Normally Closed” (or NC) type by using a gearwheel segment with a push-rod in an over-dead-point configuration. To assist an actuator made as an electric motor that acts upon the gearwheel segment a compensation spring in the form of a compression spring is articulated to the gearwheel segment, which acts during the engagement process in a rotational direction that corresponds to engagement of the clutch device. The gearwheel segment has at least two stops, with corresponding stops on a static housing of the actuating device, such that one stop corresponds to a fully disengaged clutch device and the other stop corresponds to an essentially fully engaged clutch device. Owing to its over-dead-point configuration, in the disengaged condition of the clutch device the compensation spring holds the arrangement in a stable condition in which one gearwheel segment stop is in contact with the associated stop of the housing. The possibility of providing two actuating devices in association with a dual clutch device in order to actuate two clutch assembles independently of one another, is mentioned.
Various designs for spindle-type actuating devices for dual clutches are known from DE 102 38 118 A1, EP 1 400 716 A1, DE 10 2004 001 569 A1, DE 103 13 450 A1 and DE 103 48 312 A1. DE 198 51 466 A1 discloses a control element with a gearwheel segment that can be turned by an actuator, upon which a supporting spring acts to assist the actuator. The special feature of the design proposed is that the pre-stressed condition of the supporting spring can be optionally varied.
NO-type dual clutches are known, in which actuation takes place by means of an electric motor driven disengagement lever, with actuation of the respective clutch by a ramp or rocker mechanism. The clutch device and the actuating device are separate assembles apart from one another.
A problem with the systems practiced until now is that additional components are needed in order to compensate for assembly tolerances, which makes the structure more expensive and complicated, and hence more susceptible to malfunctions.
For NO clutches self-locking actuating mechanisms (whose efficiency is poor) or additional locking elements (with corresponding costs) have been proposed. To produce a permanent pre-load on an actuating element or a disengagement bearing of an actuating element that serves as a release element or an engagement bearing of an actuating element that serves as an engagement element, in accordance with conventional systems additional springs are needed.
A further drawback of conventional systems is that for clutches or possibly dual clutches of the NO type and clutches or possibly dual clutches of the NC type, as the case may be, actuating devices of respectively different kinds are provided so that accordingly, they have to be designed in detail, adapted and stocked by any manufacturer who supplies clutches of both types.